Rayner contested the Ashton-under-Lyne constituency in the 2015 general election, and increased the Labour majority and share of the vote in the constituency.[14] She delivered her maiden speech in the House of Commons on 3 June 2015. Rayner successfully defended her Ashton-under-Lyne seat at the general election called on 8 June 2017 both increasing the Labour Party majority and vote share.[15]

On 27 June 2016, she was promoted to Shadow Women and Equalities Minister, and was further promoted later that week to Shadow Education Secretary, as Jeremy Corbyn reshuffled his shadow cabinet following a string of resignations.[11] Rayner had previously served as Opposition Whip and Shadow Pensions Minister.

Rayner is concerned that statutory instruments enable the government to bypass parliament and fears this is a threat to democracy. Notably, Rayner is concerned that the government in 2017 raised tuition fees by statutory instrument and disregarded a later vote in parliament against this rise. Rayner fears similar statutory instruments may be used to bypass parliament over Brexit.[17]

On 24 October 2017, Rayner referred to Conservative MP and government whip Chris Heaton-Harris as a "pound-shop McCarthy" in reference to his letter to UK universities regarding their teaching on the subject of Brexit.[18]

Rayner blames the government for a shortage of teachers in UK schools. She said, "Slashing" teachers' salaries meant, "fewer people are training to join the profession, and teachers are leaving our schools in record numbers."[19] Rayner said, "[A high percentages of teachers leaving the profession] is the latest evidence that the Tories have created a crisis in teacher recruitment and retention, yet ministers continue to bury their heads in the sand. The next Labour government will create a National Education Service, providing the funding our schools need and the pay our teachers deserve."[20]

Rayner is concerned that 44% of education authorities have inadequate provision for children and young people with special education needs and disabilities (SEND). Rayner stated that years of "brutal Tory cuts to services" were harming those most in need of support. "When the government's own inspectors say that the most vulnerable children are being let down and deserve a better deal it is clear that there is a serious problem."[21] Rayner also complained about, "devastating cuts" in SEND provision forced onto schools and local authorities. She said, "It has brought services for children with special educational needs and disabilities to a dangerous tipping point. Despite the prime minister's promises, it is clear that austerity is not over for our most vulnerable children."[22]

Rayner is concerned that colleges of further education will have to pay pension provision for their staff. Rayner stated, "The Treasury is imposing new unfunded pension costs of £80m a year from 2020, amounting to more than £300,000 per college. So I want to reiterate our call on the government to give all schools and colleges the certainty they need and guarantee that their budgets will be protected from these stealth cuts."[23]

In 2010 she married Mark Rayner, a UNISON official.[6] She has three sons: Ryan, who was born when she was aged 16, Jimmy, and Charlie.[7] Charlie was born prematurely at 23 weeks and Rayner says that the care he received demonstrates the importance of the NHS and education policy.[12][24] Rayner lives in her constituency of Ashton-Under-Lyne with her family.

In an interview with Evan Davis as part of the BBCNewsnight television programme broadcast on 24 September 2018, Angela Rayner said that her mother was unable to read or write; a repeat of part of a tribute she made to her mother in 2016.[26]

In March 2019, Rayner revealed that she had to fit panic buttons at her home after rape and death threats were sent to her a few weeks prior.[27]